1. Field of the Invention
The present invention relates to a mobility proportion current generator, a bias generator and an amplifier using CMOS technology.
2. Description of the Related Art
In recent years, miniaturization and cost reduction of mobile radio terminal equipment represented by cellular phones have been moving forward energetically.
It is effective for realizing miniaturization and cost reduction of the mobile radio terminal equipment to fabricate a radio transceiver circuit which performs a transmit and receive process in a RF band in a integrated circuit.
It is desirable to use, as elements comprising the integrated radio transceiver circuit, MOS transistors suitable for high integration in comparison with bipolar transistors. The radio transceiver circuit of the mobile radio terminal equipment uses many amplifiers.
In these amplifiers, the transconductance of transistors comprising the amplifier varies with temperature. For this reason, the transconductance of the whole amplifier has temperature dependencys. When the amplifier has the temperature dependencys, it is necessary for making the amplifier operate stably to perform adjustment outside of the amplifier for compensating for the temperature dependencys. This temperature compensation prevents cost reduction of the radio communication equipment such as mobile radio terminal equipment including amplifiers using MOS transistors.
As described above, a conventional amplifier using MOS transistors has problems that the transconductance has a temperature dependency.
It is an object of the present invention to provide a mobility proportion current generator which is suitable to compensate for the temperature dependency of an MOS transistor, a bias generator using the mobility proportion current generator, and an amplifier using the bias generator.